Using computer graphics software to accurately visually render the appearance of a local geographic environment in the view of a fixed observer (from a particular viewpoint chosen by the observer) is in itself a challenging task because of the difficulties involved in accurately simulating the various textures and graphical details of a scene in addition to the problems of reconstructing a scene according to the observer's viewpoint. However, modern visual navigation systems under current development place a far greater demand on graphics software: to accurately simulate the visual environment of a moving observer to serve as a navigational aid. Using rendering software to depict the local geographic environment of a moving observer, such as a driver in a vehicle, in real-time is obviously far more challenging than rendering the environment of a fixed observer, because as the location of the observer changes, the geographic objects within his or her viewing horizon and the appearance of these objects change, requiring a continual updating mechanism by which new graphical objects (local “points of interest”), textures, features and views and other reference data can be readily downloaded to accurately render and provide information pertaining to the local navigated environment in real time.
Some visual navigation systems currently in use provide three-dimensional visualizations of real environments based on user input, but these systems either do not support mobile navigation, and thus do not provide route guidance applications for navigational assistance, or are limited in terms of the renderable viewpoint or the graphical features that can be displayed.
What is therefore needed is a visualization system for mobile units, such as motor vehicle navigation systems or personal digital assistants (PDAs), that realistically renders the environment of a mobile observer with a high degree of detail according to any viewpoint, and also provides navigational aids such as route guidance and reference information pertinent to displayed objects.